First version of Primawera

See merge request !10

feat(canvas3d): synchronize other views with the main view.

See merge request xpetrus/primawera-test!9

Since sometimes numpy creates a view instead of copying the data, it was possible to use this behaviour to change the raw data inside the object. I was not able to find the exact condition when this happens as it seems to happen randomly.

It was not possible to apply LUT after a filter.

When LUT is active, some filters become invisible.

feat: Attaching with IPython event loop.

See merge request xpetrus/primawera-test!8

The app now checks if it is already running inside an QApplication instance. In which case it does not start the `exec_` function. That means that IPython can attach to Qt's event loop, hence creating the main application does not block the interactive shell.

ComplexCanvas now allows the user to just view the real or the imaginary part of the data.

Division by zero in linear_stretch.
Negative numbers in logarithmic stretch.

Fixed a bug where pixmaps where generated before activating a filter, which was wasteful.

feat: Images are now longer mapped to range [0,1] while processing and floating point image data no longer has 'None' filter.